Supercharger for internal combustion engines



June Z9,

1937. o G. scHRoM 2,085,547

SUPERCHARGER FOR INTERNAL COMBUSTIN ENGINES Filed April 30, 1935 5 Sheets-Sheet ly /111'1'111I.I11,111...'l'.1,111'1111.1111111101111 a.

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SUPERCHARGER FOR INTERNAL COMBUSTION ENGINES June 29, 1937.

Filed Ap ril 30 1935 3 Sheets-Sheet 2 .ufvlllllil/ .lll .EME/$45. I

Iliff' ll INVENTOR 'ATTORNEYS 4 infiniti;

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o. G. scHRoM 2,085,547 SUPERCHARGER FOR vINTERNAL COMBUSTION ENGINES June .29, 1937.

3 Sheets-Sheet 5 Filed April ,50, 1935 INVENTOR BY M NEYs UNITED STATES Patented 'June-2.9, 19.37l

'PATENT--LOFFICE-j l 7 Claims.

This invention has particular reference to the provision of an improved supercharging device-for use on atwo-cycle internal combustion engine of Diesel type and'I .have shown it 'particularly as applied to' the engine structure shown in my co- `pending application Serial No. 17,759, filed Aprilv 'The generall construction of the engine is substantially the same as that shown in said copending application, i. e., as inthe previous case,-I employ -the arrangement of twov opposed pistons connected byl connecting rods to a three-throwv crank and having .above the' upper piston and operatively moving therewith a scavenging piston of larger diameter than the working pistons. The

" improvements 'in the present case reside in an arrangement of parts by which the air charged into the cylinder of the working'pistons will be' augmented in pressure or supercharged. I also contemplate advancing the crank on the maincrank shaft for the lower working piston rather than having-1t directly opposite or at 180 'to the cranks v for the upperworki'ng piston and scavenging piston. This arrangementis advantageous in that 2,5 it enables the exhaust ports and scavenging ports to be so dimensioned in length that they will be covered and uncovered. at such points in the cycle as will give themost effective results.

.It is known that the power output of a Diesel j 3o engine is proportional to the pressure oi the air.

' enclosed in the working cylinder at the beginning of the compression stroke and this pressure underl 'conditions otherwise similar isy itself pro-- portional to the initial pressure at which thelillling of the working cylinder with air takes place. In my earlier application the cylinderfof the engine described ,does not chargethe working` I-t is cylinder with pressure above atmospheric.

one o f the objects o f this present invention to provide for such supercharging effect -in an engine of the type set forth in the previous application.

In carrying out this invention I have embodied my improvements in a" structure shown in the Figure 3 is a horizontalA section taken on the 5. une 3 3 of Figure 1`. 4 .Figures 4 to 10 inclusiveshowdiferent positions of the moving parts-in the peration of the j engine, and

.55 Figure 11 is a partial sectional Viewl with a proipherie pressure to provide the desired charging eiect.'

jection at the left giving the card o fthe compressioncharge of the scavenging piston.

The various positions and movements of the parts shown in Figuresfi to l0 are generally sirnilar to those shown inr ny-previous application 5 Serial No. 17,759; However, gures are included to .illustrate the manner in which superchar'ging is obtained through mynovel construction of the scavenging piston; cylinder and associated ports. The arrangement is illustrated more particularly 1 0 in Figures 1', 2, and -3. 'As will be clear from these figures and from the -following `description I have provided a means whereby the scavenging pistonn'ot only operates to accomplish scavenging but in addition serves .to chargethe working 15 cylinderwith air'- under pressure above atmossuper- By my improved arrangement I -am 'enabled to so dimension the exhaust ports with respect tolgo the scavenging ports that the scavenging ports will be uncoveredand the'exhaustgports covered by the piston in that part of the cycle Where the supercharging is to be eiected whereby air urider higher pressure than atmospheric will be de-l 25 livered from the scavenging pump tothe working cylinder as' a supercharge. The particular arrangement of the crank shafts illustrated in the drawings is advantageous in 4bringing about this result. A

Referring to the drawingsI have'illustrated an engine casing II and-a cylinder I2 containing opposed pistons I3 and I4, the lower piston I3 being connected by connecting. rod` I5 to va crank I6 and the upper piston I4 being connected by 35 a couple of connecting rods -II to cranks I8.. Above the upper working piston and connected with` it so as .to move in unison is a scavenging piston I9 working'in a-cylinder 20 and provided with air inletv ports 2 I', this constituting the scav- 40 enging pump, thev piston of Which controls the air inlet ports 2'I. This isA the same construction as in my said previous application.

In'this present invention, however, I provide additional ports in the cylinder of the scavenging pump located at 21, therebeing a plurality of these ports arranged around the walls of the .cylinder as clearly shown in Figures 1, 2, and 3.

Referringto the drawings it will be seen that in Figure 5 the air inlet ports -2I have just been 50 covered so that the airin thechamber-above l' the piston andin the receiving chamber 25 is at atmospheric pressure. From this point onthis u air is compressed and when .the piston I9 reaches the position shown in Figure 6, the air inthe 55 v v*chamber above the piston is well compressed as the scavenging cylindera'nd with the scavenginis also `tlieair in the receiving chamber 25, it being noted that the working piston I4 at thistime still' covers the port 26v at the bottom of the receiving chamber 25. I

As the piston I9 continues its upward movement there is a slight interval when both the port 21 and the port 26. are open, but this is not sufficient to allow the air pressure in the 1o space above the piston I9 to drop to atmospheric because of factors such as the short time element, theproportion of partsfthe resistance to flow and the presence of sluggish burnt gases in the working cylinder. When such factors are considered it willI be realized that the pressure of the air in the chamber above the piston I9 is not reduced to atmospheric. It will thus be seen that when the piston I9 is in the position shown in Figure '7 in which it'has just covered the 'port 21, air at pressure above atmospheric isfconiined in the space above the piston. In this position the port 26 is uncovered as is also the exhaust port '24 so that the working cylinder is cleared of burnt gases,

As the piston I9 continues its upward movement to the position shown in Figure 8 and from thence downward to the position shown in Figure 9, nothing is gained in the way of added pressure in the upstroke because this pressure is lost in 30 the equivalent downstroke. However, when this additional upstroke started, the air was above atmospheric and, therefore, when the piston returns in downstroke to the position shown in Figure 9, the air is still at the same pressure above atmospheric that it was at when it started the additional upstroke, thus making air at above atmospheric pressure available for supercharging purposes.

While the additional up and down stroke of the piston represented in Figures '7, 8 and 9 has no utility insofar as increasing pressure is concerned, it has,l however, decided utility in a mechanical sense because it is during this portion of the engine cycle that the lower working pletely clear the working cylinder o f burnt gases piston I3 keeps the exhaust port 24 open to com` and then iinally'moves upward to 'the position the-exhaust ports 24 are closed. Thus the air inlet ports 29 and exhaust 24 open. Thus pressure air from the receiving chambers 2l scavenges the cylinder and air under pressure is confined lin the space above the scavenging'piston.

Figure 8 shows the parts advanced with the scavenging piston in* its extreme upper position. and with the ports 21 still covered and ports 29 and 24 stiliopen.

Figure 9 shows the scavenging piston and con--v nected parts as they travel down 'far enough to begin to reopen the discharge ports. 21, at which time the inlet ports 29 are still partially open but 15 under pressure enters the working cylinder as a supercharge.

Figure l0 shows the beginning of the compression stroke. Between Fig. 10 and Fig. 4, the charge has been compressed, and just previous to the position of elements in Fig. 4, the compressed charge has been exploded.

Figure 11 shows in the diagram the cycle of pressures, a being the lowermost position where the pressure above the scavenging piston is slightly below the atmospheric line; b shows the atmospheric line from which the pressure in the scavenging lcylinder and receiving chamber rises until the point c is reached and then drops to the point d on further upward movement of the scavenging piston due to the opening of the scavenging ports 26, then again rising to point e where the scavenging piston is at its topmost position, then the air expands due to the downward movement of'the scavenging piston to p'oint l from which it strikes the point g at which the upper working piston closes the scavenging port 26.

The travel from ,f to g represents the supercharging period in the cycle,v i. e., when the scavenging piston arrives at the point g the working cylinder has been charged with air above atmospheric pressure. vThis point also is the beginning of the compression stroke with the initial pressure in the working cylinder being above atmospheric. It will thus be seen that I have provided a very effective and' simple arrangement for supercharging engines of the character described. It is also to be observed that the chargclean air at atmospheric pressure is present in of the power stroke. Y

Figure 5 shows the parts just as the air inlet ports to the'scavenging cylinder close.

Figure 6 shows the parts with the exhaust 24 open from the power cylinder and the scavengn ing inlet ports at' the top just beginning to open.

Figure FI shows the parts with idle/scavenging piston just closing the discharge'ports 21 from Figure 4 shows the parts `lust at the beginning' ing of the scavenging cylinder takes place during the movement of the scavenging piston from point h. to i. to b.

1. A supercharged internal combustion engine having upper land lower working pistons and cylinder, a scavenging piston and cylinder, said scavenging piston being connected with the upper working piston to move in unison therewith,'the ports in the wall of said scavenging cylinder so located as to be uncovered by the scavenging `pistn when it is at the bottom of its stroke, outlet ports in the wall of the scavenging cylinder positioned to be closed by the scavenging piston prior to its reaching the upper linut of its stroke. a Vreceiving chamber with which said outlet p'orts communicate, outlet ports from the receiving chamber to the. working cylinder, means for admitting fuel to the king cylinder, and exhaustA portsleading from t e working cylinder, crank y means for said cylinders, said crank means being so proportioned 'and seid ports so relatively 1ocated thatair under pressure is admitted to the working cylinder from'the scavenging cylinder as a supercharge.

2. A supercharged internal combustion engine 75 z 2,os5,547

outlet ports of the :scavenging cylinder and 'ref having yupper and lower .working pistons and cylcommunicate, outlet ports .fromthe receiving' .chamber to the Working cylinder, means for admitting fuel'to the working cylinder, andex'- haust ports leading from the -working cylinder,

" crank means for said cylinders, said crank means.

inder, a scavenging piston and cylinder, said scavenging piston being connected, with 4the upper working piston to move in unison therewith, inlet ,ports in the lwall of said scavenging cylinder so located as to be uncovered by the scavenging piston when it is at the bottom of 'its stroke, outlet ports in the wall of the'scavenging cylinder posivtioned to be closed by the scavenging piston prior toits reaching the .upper limit of its stroke, a receivin'g. chamber With'which said outlet4 ports being so proportioned and said ports so relatively located that the working cylinder exhaust ports are covered bythe-lower working piston andthe outlet ports of the scavenging cylinder and re.

ceiving chamber are uncovered4 by the'scavengin'g piston and'upper piston during al portion ofthe ycycle of the engine whereby'air under'pressure is admitted tothe working cylinder as a supercharge. r

3. A supercharged internal combustion engine having upper and lower working pistons and cylinder, a scavenging piston and cylinder, said scavchamber to the working cylinder, means for admitting fuel tothe working cylinder, and exhaust ports leading from the working cylinder, crank means for said cylinder, said crankmeans being Y so proportioned and said ports so relatively lolcated that the workingcylinder exhaust ports are covered by the lower Working piston and the outlet ports of the scavenging cylinder and ret' ceiving chamber are uncovered by the scavenging piston and upper piston during a portion of the cycle of the engine whereby air under pressure is admitted to the vworking cylinder as a supercharge, said crank means including a crank having connection with the lower piston and a crank having connection with the upper'piston disposed ,approximatelyl80 apart.

4. Av supercharged internal combustion engine having upper and lower working. pistons and 4 cylinder,l a scavenging piston andl cylinder, said :piston prior to its reaching p the upper limit of its stroke, a receiving chamberwith which said outletl ports communicate, outlet ports from the` scavenging piston being connected with the upper working pistonA to move in unison there.- with, inlet ports in the wall of said scavenging cyl- -inder so located asy to be uncovered bythe scavengingpiston when it is atv the bottom of its stroke, outlet ports in the wall of the scavenging cylinder. positioned to be closed by the scavenging receiving chamber to the working cylinder, means for admitting fuel to the .working cylinder, and exhaust ports leading yfrom the working cylinder, crank means for. said cylinders, said crank means :being so' proportioned and said portsso relatively located that the working cylinder exh st ports are covered by the vlower working pist/@Tand the ceiving chamber are uncovered by the scavenging piston and upper piston during a* portion ofthe cycle ofthe engine whereby air under pressure is admitted to the working 'cylinder as a supercharge, said crank' means including a crank hav- .ing vconnection lwiththe upper piston and a crank l having connection with the lower piston, said second mentioned crank being lsubstantially opposed to' the first-mentioned crank but advanced with respect thereto` in the direction of rotation.

5. Asupercharger for internalcombustion engines having a pair of opposed working pistons,

a cylinder for said pistons, a scavenging piston,

a scavenging piston chamber, inletports in the lower portion of the wall of the scavengingpiston chamber so'located as to be 'open when the.

scavenging piston is at 'the bottom of its--stroke and to be closed by said scavengingpiston in the first portion of itsup-stroke, and outlet ports in the upper portion ofthe wall of said vchamber so located as to vbe closed by the scavenging piston before said pistonhas reached the end of its up. stroke. f

6. A Asupercharged internal combustion engine I having upper and lower working pistons andcylinder, a scavenging piston and cylindensaid scavenging piston being connected with the up-v per working piston to move in unison therewith,--

air inlet ports inthe wall of the scavenging cylinder positioned to be uncovered by the'scavenging piston'when it is inthe lower portion of its stroke, outlet ports in the upper portion ofthe wall of the scavenging cylinder controlled by the scavenging piston, a recel-ving chamber withv which saidoutlet lports communicateV outlet portsV from Vthe receivingchamber tothe working A cylinder controlled bythe ,upper working piston,

exhaust ports leading ,from the working cylinderl controlled by the lower working piston, crank means, means connecting said pistons to the crank means, said ports being so relatively lo-. -l cated that in one portion lof the`cycle of the en- 'gine the outlet. ports which connect the scavenging cylinder and receiving chamber areuncovered by the lscavenging piston, the outlet ports'- l which connect the receiving chamber and working cylinder uncovered by the upper working pis- 7. A vsupercharged internal combustion engine comprising a power cylinder having ports for the .ton and the exhaust ports leading from the working cylinder covered by the lower working piston.

admission of air underpr'essure and portsfor the exhaust of burnt gases, an'upper and a lower power piston in said cylinder the upper of whichcontrols said admission ports and the lower of which controls said exhaust ports, aM crank l shaft operatively connected with both pistons, a

scavenging piston connected to said upper power piston,.a cylinder for. said scavenging. piston,

'ports in thelower portionof the wall of said scavenging cylinder for the admission of atmospheric airadapted to be covered and uncovered by the scavenging piston in the lower portion of its stroke, outlet ports in the upper portion'of Athe wall of said scavenging cylinder adapted to be covered by the scavenging piston p'rior'to its reaching the end of i up-strokeand to be uncovered by said soave ging piston in the early portion of its down-stroke, .a chamber connectand means foradmitting fuel into the-power cylinder. y OSCAR G. SCHRONL ing the outlet ports ofthe scavenging cylinder with the admission ports of the power cylinder,

CERTFCATE 0F oRREeTIoN.

Paten; No. 2,085,547. June 2e, i937.

OSCAR G. sCHRoM.

It is hereby certified that error appears in the printed specficaion of the above numbered patent requiring cerrecjion as follows: Page 2, second column, line 57, claim 1, for "the" read inlet; and that the said. Letters Patent should be read with this correction therein that the same `mayconorm't the record of the ease in the Patent Office.

Signed and sealed this 31st day of August, A. D. 1937.

. v Leslie Frazer (Seal) Acting Commissioner of Patents. 

